package Huawei;

import java.util.Scanner;
import java.util.TreeMap;

public class HJ8合并表记录 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        TreeMap<Integer, Integer> map = new TreeMap<>(); // 输出结果要求有序！

        while (sc.hasNextInt()) {
            int n = sc.nextInt();
            for (int i = 0; i < n; ++i) {
                int a = sc.nextInt();
                int b = sc.nextInt();
                map.put(a, map.getOrDefault(a, 0) + b);
            }
        }
        for (Integer i : map.keySet()) {
            System.out.println(i + " " + map.get(i));
        }
    }
}
